Foldable frame for screens



Dec 19, F550 A. v. DITTY FOLDABLE FRAME FOR SCREENS 2 Sheets-Sheet 2Filed May 26, 1945 iii (Ittornegs I Patented Dec. 19, 1950 AllanV..-Ditty,-'Grosse Pointe, Mich., assignor, by mesne,-assignments, toArthur J Bradford, Chicago, .Ill.

Application-Ma'y -26, 1945,:Serial 16055965023 ZCIaims. 1

This. invention relatesto collapsiblescreens; and particularly toa'rfoldablevframe =for projection screens for use with opticalprojection appa- 'ratus.

One object of this invention is to :providea col- :lapsiblescreen with;a foldableframe havingan extensible and collapsible support, the;opposite portions of .which. aremechanically synchronized so as to beextended and :retracted in unison.

Another object is to provide =a.foldable.'frame for a screen supportedby ,pivoteid .arms which are, mechanically interconnected bya mechanismwhich positively guaranteesitheir beinggextended and retracted insynchronism.

,An'other obie-ctqis to provide a-gioldable frame for a screen zassetforth.inlthejpreceding :ohject 'Whereinmeans-is provided by @thesamemechanism for holding the arms in theirrextended positions withoutdanger of accidental collapse.

Another object is to provide a :fold-ableframe iorca screeny-having aflexible. sheet capable of being wound upon a roller and 'ha-Vingasupporting-bar along one edge connected .topivoted arms whicharemechanically interconnected to 'be ,extended :and retracted inunison.

.Anot-her objectis to provide a 'foldable frame for :a screen asset.forth. in j-the preceding object whereinrtheerms and bar are. adapted tohereceived in the housing whichwcontains the. roller.

.In the drawings:

jFigurel is a rear elevation of apreferred embodiment of the-oollapsibleaframe for a screen of the ipresentinvention, with'a.portion of the housing broken away to expose thellower'en'ds of thesupporting arms, and with "the screen .extended.

.Figure 2 is a right-handside elevation of the screen shown in Figure11.

Figure 3:is.a rear elevation similar to Figure 1, :but with thescreenretracted and collapsed.

Figure 4 is a horizontalsection through the screen of-Figure 1takenaalongthe line '44 therem.

Figure '5 is a fragmentary .vertical: longitudinal sectionthrough thehousing WiththescreenQeX- tended, taken along the :broken line 5-15; in.Figure 4.

Figure 6 -is a verticalcross-section through-the screen housing with thescreen extended, taken along'the line :6-6 in Figure 1.

.Figure'? is a cross section similarto. Figure-6, but with the screenretracted .into its housing.

Figure 8 is aleft-hand end elevation r-of the screen housing of Figure 1with the screen -extended.

Figure 9 (-is a horizontal section through the pivotal connection of'the supporting arms, taken :along the line 99,in Figure 1.

Fi ure :10 is-a vertical section through the-piv- =otal;'connection-of;one set of the sup orting arm-s takenalong-the line !.!-l6 in/Figure:2.

In eneral, the -invention consists of 1a flexible sheet member WhiGhjiSwound 1upon ,a'-r.0 11er in a yhousing. The sheet member is ;;providedwith a supporting bar a'longyi-ts upper oriree edge. To this {bararegsecured :a pair of ydownwardly ;ex-- tendinglarms .pivotallyconnected ;to the :upper ends ofyagpa'ir of upwardly extendingarms :piv-=ot'a1ly mounted on a bracket-in the; screen housing. The upper ends..ofs-the IAPDBIJfll-IIlSfflIld the :lower. ends of.a:the lower arms'areinterconnected by toothed gearing in such a manner that the two sets. ofarms will be extendedand retracted in unison. When retracted, the"pivoted a'rm's told-downward into the housingas the screen is wound upon="the roller, a-nd the bar comes down onftop of the housing.

Hitherto, it has been difficult to provide -a collapsible screenwhereinthe opposite ends-0f the screen'proper would always be eXtendedto-the'samepositions; thereby preventing wrinkles; and also wherein theextended sc'reenwould, he rigid- 1y supported without sagging and yetwould be capable of instant retractionin'to a small housing. "The screenof the present invention-overcomes theseprevious .difiiculties, andsolves the problem by providing apair of sets of pivoted arms whicharejgeared together torise andffalll in unison. 7

Referring-to ,thewidrawings in detail, Figure l shows apre'ferredembodiment of .theffoldable Jframefor a screen havinga 'boxelike housinggenerally .designated le with; a screen member generally designated] 1 vcapable of being wound upon a roller, generally designated-l-2andsustained in its extendedposition by a supporting vstr ucturegenerally. designated I3.

Thehousing Ill is inthe form of abox having abottom 14,.front andreariwalls. l5land N; (Fig-- ures 6 and 7)., a toplland ends. Band H).The ends 18 and 19 are provided with apertures 20 fromwhich tubularbracketsZl and 22 extend inwardly-and are secured by rivets 23-to theends t8 ,and. I9. lbebracketZ-i is provided with an -elongated holeflandthe bracket 22 with .a circular hole 2 5.

Theholes 2-4 andf25 receive thecorrespondingly shaped-end pins 2-6and-21 respectively (Figure ,-5)

r of the roller. The pin 2 'l of circular GI'QSS? edges 58 of thechannel arms 52.

section is inserted directly in the end cap 28 at one end of the rollerwhereas the pin 26 of elongated cross-section is at the end of a shaft29 passing loosely through a bore 30 through the other end cap 3| andhavin an enlarged head 32 engaging an enlargement 33 at the end of thebore 30. The shaft 29 at its inner end is provided with a head 34 havinga socket 35 for receiving the inner end of a spiral spring 36, whichencircles the shaft 29 and has its opposite end secured in a socket 3'!in the end cap 3|. The end caps 28 and 3| are interconnected by a hollowtubular roller barrel 38 rigidly secured thereto as at 39.

The roller barrel 38 is provided. with a longi tudinal groove 46 (Figure6 and '1 within which is anchored the inner edge 41 of the screen memberH, as by the retaining bar 42 secured to the roller barrel 38 as at 43.The opposite edge of the screen member-H is wound around a tubularcross-bar 44 and secured to itself as at '45 (Figure '7) by a suitableadhesive or other means. Secured as at 46 to the center of the tubularcross-bar 44 is a bracket 4'5 which extends over the top of thecross-arm 44 and has a downwardly extending arm 48 forming a plate withapertures 49 (Figure '7) for receiving a pair of threaded studs 50.These studs 56 pass through apertures 5| in a pair of upper channel arms52 forming the upper portions of the supporting structure [3. Each studwithin the channel portion of the channel arm 52 carries a quadrant gear53 meshing with the quadrant gear 53 on the other stud 56 (Figure 1).The quadrant gears 53 are firmly secured to the channel arms 52 by thepins 54 passing through both.

The channel arms 52 are pivoted to the lower arms 55 by means of pivotpins 56 passing through apertures 51 in each pair (Figure 10). Thechannels in the channel arms 52 face inwardly toward one another, andthe pivot pin holes 5'? are so arranged that when the screen is extendedto its fully raised position, the lower arms 55 move past the positionof alignment with the channel arms 52 and come to rest against the lowerback In this way the pivoted arms 52 and 55 are moved past dead centerinto self-sustaining positions.

The lower ends of the lower arms 55 are provided with bores 55 (Figure6) for receiving a stud bolt 60 passing therethrough and through anaperture 5! in an angle bracket 62 secured as at 53 to the bottom E4 ofthe housing ill. The stud bolt 60 also passes through the side wall E6of the housing I D and is provided with lock nuts 64 and 65 on oppositesides thereof. Mounted on the stud bolt 86 and secured as at 66 to thelower arms 55 are two meshing gears 61 which operate in a similar mannerto the quadrant gears 53 described above (Figure 5).

In operation, to extend the screen from its folded position of Figure 3the operator pulls 'upward on the tubular cross-bar 44 of the bracket41, causing the upper and lower arms 52 and 55 to move from the positionof Figure 3 upwardly into the positions of Figure l, meanwhile crossingthe aligned position just prior to halting with each lower arm 55 comingto rest against the back lower edge 58 of each channel arm 52. As thearms 52 and 55 swing upwardly and their pivots 56 swing in arcs from theouter ends of the casing l0 (Figure 3) to the central positions of Fig.1, the intermeshing teeth of the gears 53 and 61 drivingly interconnectthe two 4 sets of arms 52 and 55 in such a manner that the arms move inunison.

Since the pivots 5D, 56 and 60 are spaced laterally from each other, thecross bar 44 is supported, in effect, by a pair of rigid but foldablespaced pillars. The geared interconnection of the two sets of arms 52and 55 prevents one set of arms from moving independently of the otherset, hence the cross-bar 44 is raised and lowered by a linkage whichcauses it to move through successively parallel positions. As the screenmember I l is raised and unwound from the roller i2, the coil spring 36(Figure 5) is wound up and stores up energy. This maintains the screenmember II in a taut position. The screen member I l is preferably madeof a resilient material, such as white rubber, so that it is free fromwrinkles and maintains itself in that condition.

To lower the screen member II, the operator grasps the supportingstructure l3 adjacent the pivots 56 and pushes the latter away from eachother. The pivots 56 and arms 52 and 55 then move past their alignedposition and downwardly into the folded position shown in Figure 3. Hereagain the intermeshing gears 53 and 61 cause the arms 52 and 55 to movedownwardly in synchronism, causing the cross-bar 44 to move downwardlythrough successive parallel positions. The cross-bar 44 comes to restimmediately over the slot 68 in the top I! of the housing ill, partiallyclosing this slot. The screen is thus foldable into very compact formand is protected by the housing It against dust and damage.

While a specific embodiment of the invention has been described andillustrated, it will be understood that various modifications may bemade within the scope of the appended claims without departing from thespirit of the invention.

What I claim is:

l. A foldablevframe for a collapsible screen comprising a base, a crossbar spaced above said base, and two pairs of foldable uprights arrangedadjacent one another and having their lower and upper ends pivotallyconnected to the central portions of said base and cross barrespectively, each of said uprights including a lower and an upper armhaving a common pivotal connection to one another and disposed alongsideone another in the folded position of said arms, said common pivot lyingsubstantially at the outer extremity thereof, one of said arms having anextension overlapping the other arm beyond said common pivot and havingan abutment engageable with said other arm at a location spaced awayfrom said common pivot when said arms are extended, said common pivotand said abutment being disposed inwardly of a line joining the centersof the pivotal connections of the upright with the base and cross barrespectively when said frame is fully extended, thereby rendering saidframe self-sustaining in its fully extended position.

2. A foldable frame for a collapsible screen comprising a base, a crossbar spaced above said base, and two pairs of foldable uprights arrangedadjacent one another and having their lower end and upper ends pivotallyconnected to the central portions of said base and cross barrespectively, each of said uprights including a lower arm and an upperarm having a common pivotal connection to one another, one of said armsbeing of channel cross-section and the other arm being received withinthe channel portion thereof in the folded position of said arms, saidcommon pivot lying substantially at the outer extremity 2,534,960 5 6thereof, one of said arms having an extension REFERENCES CITEDoverlapping the other arm beyond said common The following referencesare of record in the pivot and having an abutment engageable with fileof this patent: said other arm at a location spaced away from saidcommon pivot when said arms are extended, 5 UNITED STATES PATENTS saidcommon pivot and said abutment being (115- Number Name Date posedinwardly of a line joining the centers of 1,116,562 Calmes Nov. 10, 1914the pivotal connections of the upright with the 1,820,739 Heck Aug. 25,1931 base and cross bar respectively when said frame 1,915,944 NagelJune 27, 1933 is fully extended, thereby rendering said frame 101,946,639 Ridden Feb. 13, 1934 self-sustaining in its fully extendedposition. 1,981,444 Wittel Nov. 20, 1934 ALLAN V. DITTY.

